It's because there's active contact with our world and dimension in both Ciel nosurge and here: the people of that world call their own world "Ciel", while they call ours "Earthes", as it can be seen in the BIOS-startup screen at the beginning of the opening video. And it happens to be that the robot is called "EARTHES" too, so the most commonly believed theory is that EARTHES is actually an avatar for the player due to being the terminal the player used to communicate with Ion in Ciel nosurge being remodeled by her into the robot we see here.

I figured as much given how Ciel no Surge was basically a dating sim, and how much the non-robotized main character seems to be hanging with the other female lead a lot more than Ion.

Yeah, actually. Ciel no Surge is a...non-standard game with an episodic structure that functions kind of like an odd visual novel, for a rather badly performing console. I would like it to come out, but I understand why it probably won't.

Ar no Surge, on the other hand, is a PS3 RPG that apparently has some direct connections to Ar Tonelico. It sounds pretty likely to me.

Yeah, actually. Ciel no Surge is a...non-standard game with an episodic structure that functions kind of like an odd visual novel, for a rather badly performing console. I would like it to come out, but I understand why it probably won't.

Ar no Surge, on the other hand, is a PS3 RPG that apparently has some direct connections to Ar Tonelico. It sounds pretty likely to me.

Unfortunately, I have to agree here. The episodic structure coupled with the social and online elements that factor so heavily in Ciel nosurge make it extremely improbable for it to ever get released outside Japan.

However, I have to also say that there's no "apparent" here with the connections between both series: Gust themselves have confirmed in Dengeki and Famitsu that both Ciel nosurge and Ar nosurge are directly connected to Ar tonelico with Shurelia's appearance in the game as well as the First Tower and the never-seen before region of Syestine, and they even have gone as far as saying that the story of Ar nosurge reveals important details on the memories Ion shows to the player in Ciel nosurge, and both become the entire basis upon which the story of the three Ar tonelico games is built. In fact, the Famitsu article explaining this stated that the story order goes: Ciel nosurge -> Ar nosurge -> Ar tonelico

Unless you hang around Ar Tonelico (the tower) you wouldn't encounter Shurelia who after her early childhood spent all her time as the tower's administrator (and going away from the tower is simply lethal for her)

With that said, the only period she would be free would be when she was less than ~12 years of age (and that's being generous).

Unless you hang around Ar Tonelico (the tower) you wouldn't encounter Shurelia who after her early childhood spent all her time as the tower's administrator (and going away from the tower is simply lethal for her)

The detail is that Cas and Delta get involved in an accident with a teleporter and end up in the Sol Ciel far in Ar tonelico's past. These are all the details Gust has given so far. However, there are other things that can be extrapolated if you have knowledge of the series' timeline and some of its backstory: Eolia (Shurelia) was born in 3031 AD, she was made administrator in 3035 AD, and she developed her love for bunnies in 3037 AD after she met Tilia. Considering her description in Famitsu, Dengeki and the official site states that she is both the administrator and a lover of bunnies, the possible timeframe for the period in which Cas and Delta appear is between 3037 and 3040 AD, the latter being the year in which the tower was sabotaged and the world pretty much destroyed (the Grathnode Inferia). And it also has to be before the catastrophe, as the room shown in the FMV where they meet Shurelia is where the Orgel of Origins (the power source for the Tower) is installed, and that place became inaccessible after that year because of the Sea of Death.